The art typically refers to systems for loading and unloading containers as “hook lift” systems and “cable hoist” systems. These systems have been extensively employed for the transport of various materials in the containers. In the usual case, the container may be loaded or unloaded upon the bed of the truck or vehicle utilizing either a hook lift system or a cable hoist system. A tilt frame member is also typically provided to assist in the loading and unloading of the containers. One typical use for such systems is in the picking up and hauling of refuse. An open top or closed top container is typically delivered to, or picked up from, a point of use with either of the systems.
In a hook lift system, the container contains a lift bar, a frame or other similar connection for engagement with a hook. When a container is full, the truck returns to the point where the container has been deposited and through the use of the hook lift system, elevates the filled container onto the truck where it may be transported, along with its contents, to a location where the container is unloaded and emptied, like a landfill or other facility. Examples of hook lift systems are found in U.S. Pat. Nos. 6,558,104; 5,601,393, 4,350,469, 3,874,537, 3,964,625, and 4,204,793.
Cable hoist systems accomplish the same loading and unloading function of the hook lift systems, but use a cable winch system like, for example, the one shown in U.S. Pat. No. 5,460,473. In this type of a system, hydraulic cylinders are typically used to move the cable about a fixed sheave attached to the vehicle hoist frame. In the fully retracted position, the cable, which is wrapped around sheaves connected to the cylinders, is at its longest affective length and can be connected to the front end of a container located on the ground. As the cylinders extend, the effective length of the cable continuously shortens as it wraps around the cylinder sheaves and then finally around the sheave attached at the front end of the hoist frame. As the effective length of the cable gets shorter, the container is pulled up and onto the vehicle, which is usually in a tilted position to facilitate loading and unloading of the container.
Another more limited and specific type of lift mechanism is found in U.S. Pat. No. 3,130,847 that uses a bail device mounted on a reciprocating carriage assembly. The bail device engages a plurality of specifically designed hook bars located and space along the underneath portion of the container. As the carriage is reciprocated back and forth along a short path at the back end of the hoist frame, the successive reciprocation causes the bail to engage the next hook bar causing the container to move forward a short distance. The reciprocation of carriage eventually pulls the container onto the hoist frame in a slow stepwise fashion.
Some tilt frames on the transport vehicles have extendable end portions which aid in loading and unloading containers in a more efficient manner. See, for example, U.S. Pat. No. 4,986,719. The distal (rear) end of the frame has a moveable portion which telescopically slides out of the frame to extend the length of the frame. These systems, although useful, have durability problems and the extendable end portions are not as strong as the tilt frame. Also, they require more floor space to load and unload containers.
Other vehicles are used to drop off and pick up relatively large metal containers, such as front loading containers, rear loading containers, air shipment containers and the like. These vehicles typically can load and transport only one container at a time and thus are inefficient if numerous containers need to be dropped off, transported and/or picked up.
One problem with these existing systems for loading and unloading containers is that they each contain only one type of mechanism to pick-up a specific type of container. For example, in the case of the hook lift systems, the vehicle can only pick up containers designed specifically to accept the hook. Likewise, the cable hoist systems can only pick up containers designed for cable based systems. Thus, companies must at a minimum maintain and operate two types of vehicles, those with hook lifts and those with cable hoists. Other container truck vehicles are limited to a specific type and size of container such as rear loading containers.
Another problem with existing tilt frame vehicle systems is that the tilt frame on the vehicle typically must be raised to a significant height for the loading and unloading of the containers and thus these systems have difficulty being used indoors or in situations where the ceiling height is low. The vehicles with extendable end portions may be used in such circumstances, but are not sufficiently durable and require more floor space for loading and unloading.
Needs therefore exist for new types of loading and unloading systems that can load, transport, and unload all types of containers, and in all types of situations and with all types of container loads, regardless of the overhead clearance.
The present invention solves these problems by providing a sliding carriage design that substantially transverses the length of the tilt frame member to allow multiple types of container and structure designs to be loaded and unloaded, and also provides a vehicle tilt frame with an end portion that is separately hinged and hydraulically actuated. The hinged end portion allows loading and unloading of containers without the necessity of raising the tilt frame to an extreme angle.